Safety device, particularly for roll-up doors

ABSTRACT

A safety device, particularly intended to be used in roll-up doors to cause reversal of the door closing movements in case an obstacle obstructs the path of movement of the door. The device comprises at least a couple of photoelectric cells which are arranged at a certain distance from the closing edge of the door leaf in alignment with the door leaf on a support arm which is displaceable in the direction of closing of the door.

BACKGROUND OF THE INVENTION

The subject invention concerns a safety device, which is intended to beused particularly in roll-up doors for the purpose of causing reversalof the closing movement of the door when an object is obstructing itspath of movement. The safety device is of the kind comprising at leastone signalling means which is arranged to emit a beam of light, a beamof sound or another kind of signalling beam and which is supported bythe door leaf some distance from the door leaf closing edge.

One example of prior-art safety devices for doors is formed with asealing strip which is positioned at the lower edge of the door leaf.The sealing strip consists e.g. of a hollow strip of soft rubber, theends of which are sealed to enclose a quantity of air in the interior ofthe strip. Should the door leaf hit an obstacle, while moving downwardsinto its fully closed position, the air inside the sealing strip iscompressed, resulting in actuation of a diaphragm valve to reverse theclosing movements of the door leaf. This construction does, however,suffer from the disadvantage that it is comparatively fragile andsensitive, since the slightest leakage makes the device inoperative.

Considering that doors of this kind are frequently damaged, for instanceby trucks and other vehicles passing through the doorway, the use ofhighly sensitive sealing strips is not very advisable. Another seriousdrawback inherent in this prior-art structure is that reversal of thedoor leaf movements is not initiated until the leaf hits the objectwhich is obstructing its path of movement.

In another prior-art structure the problem is solved thereby thatinstead of enclosing an air cushion inside the lower sealing strip aphotoelectric cell is used the beam of which is arranged to pass throughthe strip. Although this structure is leakage-proof, it still depends ondeformation of the strip for the initiation of the reversal of the doormovements.

In accordance with a third prior-art structure which suffers fromdisadvantages identical with those inherent in the first two prior-artstructures discussed in the aforegoing two copper rails are mounted onthe strip which rails are kept apart by a spring of a non-conductivematerial.

Finally, it is also known to use photoelectric cells which arepositioned closely above the floor level. Although this structure doesnot depend on contact between the door leaf and the obstructing objectfor its operation persons may easily climb over the beam of thephotoelectric cell and the forks of fork-lift trucks may pass over it,and so the device will fail to operate. This prior-art structure couldbe combined with any one of the structures referred to in the aforegoingwhich become operative to reverse the closing movement of the door leafupon contact with an obstructing object. However, combinations of thiskind suffer from the disadvantage that also in such cases contact isrequired between the door leaf and the obstructing object to make thesafety device operative, in addition to which installation thereof iscomparatively expensive because of the necessity to double the sensingmeans.

SUMMARY OF THE INVENTION

The purpose of the subject invention is to provide an efficient safetydevice which is intended for door leaves and similar structures andwhich is designed so as to be able to cause reversal of the closingmovement of the door leaf without having to touch the object obstructingthe path of the movement of the door leaf. In addition, the safey devicein accordance with the invention is designed so as to positively excludethe possibility of anyone stepping across it by mistake, which resultsin failure to initiate operation of the device, and it is also designedto completely relieve the door leaf and effect positive stopping of thedoor leaf movements within five seconds, thus fulfilling the safetyregulations laid down by the authorities.

For this purpose, the safety device in accordance with the inventioncomprises at least one signal emitting means which is arranged to emit abeam of light or a beam of sound or a signalling beam of another natureacross the width of the door leaf at such a distance from the lowerclosing edge of the door leaf that any object that interrupts the beamemitted by the signalling means causes reversal or standstill of theclosing movement of the door leaf before the edge thereof hits theobstructing object, said device being characterized therein that thesignalling means is mounted on a support arm which is slideably mountedin a holder mounted at a lower part of the door-leaf and which supportarm is arranged to abut against the floor or a stand upon closing of thedoor so that the signalling means is displaced relatively to and towardsthe door-leaf to a position at least level with the lower closing edgeof said door-leaf during the final closing movement thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

A particularly advantageous embodiment of the invention will bedescribed in the following with reference to the accompanying drawings,wherein

FIG. 1 is a front view of a roll-up door equipped with a safety devicein accordance with the invention,

FIG. 2 is a lateral, partly broken view of the door which illustratesthe device in accordance with the invention on an enlarged scale,supported by a door leaf, and

FIG. 3 is a front view of the details in accordance with FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The roll-up door in accordance with the invention and shown in FIG. 1essentially comprises a roll-up door leaf 1, two posts 2, a lower crossbeam 3, an upper cross beam 4 onto which the door-leaf 1 is wound toopen the door, a motor 5 to actuate the roll-up movements, and a safetydevice 6.

One half of this safety device 6 is shown in detail in FIGS. 2 and 3. Itessentially comprises a photoelectric cell 7, a displaceable cellsupport arm 9 which is slidably mounted in a tubular holder 8, a stoplimit edge 10 designed to determine the lower position of the arm 9, andan abutment 11 which is designed to abut against the floor when the doorleaf 1 is approaching and in its fully door-closing position. FIGS. 2and 3 illustrate the door leaf 1 in the position it occupies when it isso close to its door-closing position that the abutment 11 hits thefloor.

The safety device 6 in accordance with the invention operates in thefollowing manner. When the beam of light extending between the twophotoelectric cells 7, one at either side of the door leaf, isinterrupted during the closing movement of the door leaf 1 this movementis reversed immediately. The reversal occurs so rapidly that the loweredge of the door leaf 1 will not hit the object that obstructs the pathof the beam of light.

As alternatives to a beam of light extending between two photoelectriccells 7, a beam of sound or another kind of signalling beam extendingbetween the appropriate generating and detecting means on either side ofthe door leaf 1 could be used to indicate the presence of an objectbeneath the closing door.

In order to allow the photoelectric cells to be mounted at asufficiently high level below the lower edge of the door leaf 1 withoutblocking the way when the door is closing, they are displaceable in thedirection indicated by arrow A relative to the door leaf 1. Displacementof the photoelectric cells is achieved by arranging the photoelectriccell support arm 9 in such a manner that it slides freely in the tubularholder 8 which is formed integral with the door leaf 1. A stopper meansor limiting means 10 is attached to the upper end of the support arm 9in order to retain the latter inside the tubular holder 8 and to ensurethat both photoelectric cells 7 assume a position at the same levelabove the lower edge of the door leaf 1. When the door leaf wasprogressed so far downwards that the photoelectric cells 7 approach thefloor, the abutment 11 hits the floor whereby the arm 9 slides upwardsrelative to the door leaf. Furthermore, the device is connected in amanner ensuring that the operation thereof ceases immediately before thedoor leaf reaches it fully closed position. This avoids interruption ofthe beam of light between the photoelectric cells 7 by means of thesealing strip 12 which is mounted at the lower transverse beam 3 on thelower edge of the door leaf 1.

Finally, it should be mentioned that the invention is not limited to theembodiment described in the aforegoing but that several embodiments arepossible within the scope of the appended claims. For instance it ispossible to fit the support arm 9 with a series of vertically positionedphotoelectric cells to remove the possibility that an object which ispushed in between the beam of light and the lower edge of the door leafis hit by the door.

What I claim is:
 1. A safety device, particularly intended for use in aroll-up door, said roll-up door including a roll-up door leaf extendinghorizontally between two upright posts defining a width for said roll-updoor, said roll-up door further including an upper cross beam onto andoff of which said door leaf is wound to open and close said roll-updoor, respectively, and a lower cross beam connected to a bottom edge ofsaid door leaf, said bottom edge of said door leaf being adjacent to aplane base surface when said roll-up door is in a closed position, saidsafety device comprising at least one signal emitting means (7) which isarranged to emit a signalling beam across the width of the door-leaf ata distance below the lower cross beam on said bottom edge of thedoor-leaf so that any object, obstructing a movement of the roll-up doorinto said closed position, interrupts the signalling beam emitted by thesignalling means and causes a stopping of the closing movement of thedoor-leaf before the bottom edge thereof hits said object, characterizedtherein that the signal emitting means (7) is mounted on a support arm(9) which is slideably mounted in a holder (8) mounted on said lowercross beam, said support arm (9) arranged to abut against said planebase surface upon closing of the door so that the signal emitting meansare displaced relatively to and towards the door-leaf to a position atleast in level with the bottom edge of said door-leaf during the finalclosing movement thereof.
 2. A safety device as claimed in claim 1,characterized therein that the signal emitting means (7) are positionedin vertical alignment with the door-leaf.
 3. A safety device as claimedin claim 1, characterized therein that the safety device (6) is arrangedto be disconnected when the door reaches a position at a predeterminedlevel above the closed ;
 4. A safety device as claimed in claim 1,characterized therein that said signal emitting means are aphotoelectric cell.
 5. An improved safety device, particularly intendedfor use in roll-up doors of the kind comprising a door-leaf and anoverhead roll-up roller, said door leaf arranged to be wound onto andoff of said roll-up roller for opening and closing movements,respectively, said door-leaf extending horizontally between two uprightposts defining a width for said roll-up door, said roll-up door furtherincluding a lower cross beam connected to a bottom edge of saiddoor-leaf, said bottom edge of said door-leaf being adjacent to a planebase surface when said roll-up door is in a closed position, said safetydevice comprising at least one signal emitting means, said meansarranged to emit a signalling beam across the width of said door-leaf ata distance below the lower cross beam on said bottom edge of saiddoor-leaf so that any object obstructing a movement of said door into aclosed position interrupts said signalling beam emitted by said signalemitting means and causes a stopping of said closing movement of saiddoor-leaf before the bottom edge thereof hits said object, said improvedsafety device comprising:a support arm on which said signal emittingmeans is mounted; a holder mounted on said lower cross beam andslidingly receiving said support arm therein; said support arm arrangedto abut against said plane base surface upon closing of said door sothat said signal emitting means are displaced relatively to and towardssaid door-leaf to a position at least level with the bottom edge of saiddoor-leaf during the final closing movement thereof.
 6. An improvedsafety device as claimed in claim 5, wherein said signal emitting meansare positioned in vertical alignment with said door-leaf.
 7. An improvedsafety device as claimed in claim 5 wherein said signal emitting meansare a photoelectric cell.
 8. An improved safety device as claimed inclaim 5, wherein said safety device is arranged to be disconnected whensaid door reaches a position at a predetermined level above said closedposition.